In a large bowl, toss together rhubarb and sugar. Spread evenly on a small baking sheet and set aside for 1 hour (or longer) until sugar starts to break down the rhubarb.
Preheat oven to 300F.
Roast rhubarb for about 25-30 minutes, until tender. Let cool completely. Rhubarb can me made ahead of time. Store in an airtight container for up to 4 days.
To assemble, divide yogurt amongst 4 bowls. Top with roasted rhubarb, pecans, lavender (if using) and honey.
Recipe by Things I Made Today at https://www.thingsimadetoday.com/2017/07/03/roasted-rhubarb-yogurt-lavender/